Cranelift: 'Could not allocate minimal bundle, but the allocation problem should be possible to solve' panic

[jakubDoka]

.clif Test Case (reduced)

function u0:0() windows_fastcall {
    sig0 = (i64 sret, i64) -> i64 sret fast
    fn0 = colocated u0:4 sig0

block0:
    v1 = iconst.i64 0
    v5 = iconst.i64 0
    v6 = call fn0(v5, v1)  ; v5 = 0, v1 = 0
    return
}

Steps to Reproduce

(bug.clif)

function u0:0(i64, i64) windows_fastcall {
    sig0 = (i64 sret, i64) -> i64 sret fast
    sig1 = (i64 sret, i64) -> i64 sret fast
    fn0 = colocated u0:4 sig0
    fn1 = colocated u0:4 sig1

block0(v0: i64, v1: i64):
    v2 = iconst.i8 0
    store v2, v0  ; v2 = 0
    v3 = iadd_imm v0, 4
    v4 = call fn0(v3, v1)
    v5 = iadd_imm v0, 16
    v6 = call fn1(v5, v1)
    return
}

(in cranelift directory)

> cargo run --release bugpoint bug.clif x86_64-pc-windows-msvc

Expected Result

The code I provided should be valid or at least possible to compile unless I overlooked something.

Actual Results

thread '<unnamed>' panicked at 'Could not allocate minimal bundle, but the allocation problem should be possible to solve', C:\Users\LENOVO\.cargo\registry\src\github.com-1ecc6299db9ec823\regalloc2-0.4.1\src\ion\process.rs:1268:17
stack backtrace:
   0: std::panicking::begin_panic<str>
             at /rustc/95a992a68694d8bf3959bd2c0ac27ce9e9208b59\library\std\src\panicking.rs:616
   1: regalloc2::ion::data_structures::Env<cranelift_codegen::machinst::vcode::VCode<enum2$<cranelift_codegen::isa::x64::lower::isle::generated_code::MInst> > >::process_bundle<cranelift_codegen::machinst::vcode::VCode<enum2$<cranelift_codegen::isa::x64::lower:
             at C:\Users\LENOVO\.cargo\registry\src\github.com-1ecc6299db9ec823\regalloc2-0.4.1\src\ion\process.rs:1268
   2: regalloc2::ion::data_structures::Env<cranelift_codegen::machinst::vcode::VCode<enum2$<cranelift_codegen::isa::x64::lower::isle::generated_code::MInst> > >::process_bundles<cranelift_codegen::machinst::vcode::VCode<enum2$<cranelift_codegen::isa::x64::lower
             at C:\Users\LENOVO\.cargo\registry\src\github.com-1ecc6299db9ec823\regalloc2-0.4.1\src\ion\process.rs:44
   3: regalloc2::ion::data_structures::Env<cranelift_codegen::machinst::vcode::VCode<enum2$<cranelift_codegen::isa::x64::lower::isle::generated_code::MInst> > >::run<cranelift_codegen::machinst::vcode::VCode<enum2$<cranelift_codegen::isa::x64::lower::isle::gene
             at C:\Users\LENOVO\.cargo\registry\src\github.com-1ecc6299db9ec823\regalloc2-0.4.1\src\ion\mod.rs:107
   4: regalloc2::ion::run<cranelift_codegen::machinst::vcode::VCode<enum2$<cranelift_codegen::isa::x64::lower::isle::generated_code::MInst> > >
             at C:\Users\LENOVO\.cargo\registry\src\github.com-1ecc6299db9ec823\regalloc2-0.4.1\src\ion\mod.rs:127
   5: regalloc2::run<cranelift_codegen::machinst::vcode::VCode<enum2$<cranelift_codegen::isa::x64::lower::isle::generated_code::MInst> > >
             at C:\Users\LENOVO\.cargo\registry\src\github.com-1ecc6299db9ec823\regalloc2-0.4.1\src\lib.rs:1460
   6: cranelift_codegen::machinst::compile::compile<cranelift_codegen::isa::x64::X64Backend>
             at C:\Users\LENOVO\.cargo\registry\src\github.com-1ecc6299db9ec823\cranelift-codegen-0.89.1\src\machinst\compile.rs:41
   7: cranelift_codegen::isa::x64::X64Backend::compile_vcode
             at C:\Users\LENOVO\.cargo\registry\src\github.com-1ecc6299db9ec823\cranelift-codegen-0.89.1\src\isa\x64\mod.rs:58
   8: cranelift_codegen::isa::x64::impl$1::compile_function
             at C:\Users\LENOVO\.cargo\registry\src\github.com-1ecc6299db9ec823\cranelift-codegen-0.89.1\src\isa\x64\mod.rs:69
   9: cranelift_codegen::context::Context::compile_stencil
             at C:\Users\LENOVO\.cargo\registry\src\github.com-1ecc6299db9ec823\cranelift-codegen-0.89.1\src\context.rs:173
  10: cranelift_codegen::context::Context::compile
             at C:\Users\LENOVO\.cargo\registry\src\github.com-1ecc6299db9ec823\cranelift-codegen-0.89.1\src\context.rs:185
  11: middleware::logic::Worker::compile_current_requests
             at C:\src\rust\catalyst\subcommands\middleware\src\logic.rs:686
  12: middleware::logic::Worker::compile_macros
             at C:\src\rust\catalyst\subcommands\middleware\src\logic.rs:614
  13: middleware::logic::Worker::compile_module
             at C:\src\rust\catalyst\subcommands\middleware\src\logic.rs:591
  14: middleware::logic::impl$2::run::closure$0
             at C:\src\rust\catalyst\subcommands\middleware\src\logic.rs:535
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Versions and Environment

Cranelift version or commit: 0.90.0

Operating system: Windows

Architecture: x86_64

[jakubDoka]

Seems like removing sret from return type of imported signatures makes compilation pass, Is sret supposed to be used with return value or argument is enough?

[bjorn3]

Using it as argument is enough.

[jakubDoka]

Seems like I was misusing this for a while, nevertheless resulting error is not helpful, Would it be possible to integrate some verification for signatures?

[bjorn3]

Yeah, I think we should check this in the verifier. Adding a StructReturn case to https://github.com/bytecodealliance/wasmtime/blob/95ecb7e4d440605165a74de607de5389508779be/cranelift/codegen/src/verifier/mod.rs#L1741-L1753 would work I think.